Digital Audio From Hdmi Vs Optical – Is It The Same?

Should I use Optical or HDMI Cables for Sound?

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A common question from a number of our customers recently has been whether to use Optical or HDMI when connecting equipment such as DVD Players, Blu-Ray players and Digital Televisions to their receivers.

Most customers have their Blu-Ray players, Media Players and Consoles linked to their TV via HDMI, but it is also very common for us to see a single Optical Cable running back from the TV to the Receiver. This works – and by works I mean it does send a Digital Sound Output from the TV channels and all of the other connected devices back to the Amplifier. But is this the best way to transmit Audio to your Home Theatre System?

Digital TV and Home Theatre TechnologyHorses for Courses

What is suitable for one person or situation might be unsuitable for another. Without trying to get too technical, there IS a difference between the performance capabilities of HDMI and Optical – but these will only be relevant if the equipment you are using also possesses these features.

Dolby TrueHD – An Audio Codec which delivers 100% lossless sound for movies or music designed for your high-definition home theater.

DTS-HD – An Audio Codec for Blu-ray Disc format exclusively. DTS-HD Master Audio has steadily become the standard for Blu-ray lossless audio format.

The two audio formats listed above use Lossles Audio Compression, which basically means that the exact original sound source can be recreated from the compressed data source being delivered from your Blu-Ray Player, Super Audio CD or Media Player as examples. To deliver these Audio Codecs, you cannot use an Optical Cable, as the Optical Bit-Rate limit is 1.5 Mbps, while HDMI will carry a lot more.

This is why you need to choose a HDMI cable to connect your equipment if you wish to gain the benefits of SACD, or Blu-Ray with Dolby True HD or DTS HD. You can only take advantage of DTS-HD or Dolby TrueHD if your A/V receiver supports that codec.

What if my Amp doesn’t have HDMI, only Optical?

Optical Cable connections will still achieve Dolby Digital Sound, and, especially since a great deal of installations we have done for our customers over the years are for “Out-Of-The-Box” all in one Home Theatre Systems, they still deliver a more than reasonable Surround Sound result which many people are more than happy with.

However in saying that, there are also many people who can really tell the difference which lossles audio provides over it’s compressed alternative, and here lies the reason why you would need to choose HDMI over Optical when deciding how to connect your Home Theatre System.

The way we see it, and they way we try to explain to our customers is – if your Amp has HDMI, then the best connection to use is HDMI. If your Amp does not have HDMI, then it may not be worth the expense (to most) to upgrade your whole system, and Optical Cables will still provide you with a great experience.

It is also true that (so far) soundtracks using Dolby True HD or DTS-HD don’t exist in free to air broadcast, Foxtel, Cable or satellite TV. You won’t compromise any sound quality connecting your DVD Recorder or Player, Overseas Satellite Dish, or Foxtel Cable box to your receiver with an optical (or coax) cable.

There are other benefits which come by using HDMI too…

The latest HDMI standard, v1.4, adds another useful feature – ARC, or “Audio Return Channel”. This basically means that the HDMI cable coming from your Home Theatre System can not only send the Audio and Video Signal to the TV, but it also sends the TV Audio back to the receiver across the same cable. Read our earlier post on ARC here. This eliminates the need for using an Optical Cable from the TV back to the Amplifier for hearing the TV channels through your speakers.